Deterioration of signal-to-noise ratio and nonlinear effects of optical fiber restrict communication distance. Reducing, the transmission losses of fiber and increasing the effective area of optical fiber are the main ways to overcome these two restrictive factors. Reducing the transmission losses of optical fiber improves the signal-to-noise ratio, while increasing the effective area reduces the nonlinear effects.
During manufacturing of optical fibers, after long usage of a fiber drawing furnace, the graphite in the fiber drawing furnace may accumulate a small amount of oxidation on a surface of the graphite which increases a surface roughness of the graphite. The fiber preform at high temperature generates a small amount of silica by sublimation which reacts with the surface of the graphite by forming hard particles of silicon carbide (SiC), and the particles float in the drawing furnace under the effect of the air flows in the drawing furnace. The existing fiber drawing furnace body contains, a gas disc on top of the furnace and an annealing tube on the bottom end. Inert gas is introduced in an upper portion of the fiber drawing furnace and, flows through the fiber drawing furnace into the annealing tube, thus the inert gas flows from up to down by mode of laminar flow. The main advantage of the laminar flow is that the air flows are flat and gentle, and will not cause flow disturbances in the fiber drawing furnace, nor will the SiC particles being deposited in the inner wall of the graphite. Thus, the likelihood of SiC particles contacting the optical fiber core may be reduced. A long drawing process causes SiC particles to accumulate on the inner wall of graphite, and under the influence of high temperature diffusion, the SiC particles may adversely affect a quality of the optical fiber core, such as a sudden change in the properties of the fiber.
Moreover, the attenuation coefficient of the fiber is limited by the preparation processes of the preform and also by an ideal temperature of the quartz glass. When the temperature of the quartz fiber is lowered from the softening temperature to the ideal temperature, the internal structure of the quartz glass is in an equilibrium state. When the quartz temperature is lower than the ideal temperature, the internal structure of the fiber is more strongly set and may more resistant to deformation. If internal stresses of the fiber are not fully released when the fibers reach the ideal temperature, the Rayleigh scattering caused by uneven densities of the fiber will significantly affect the attenuation coefficient of the fiber. The annealing process affects the internal stresses of the fiber. Uneven internal temperatures of the insulation annealing furnace may cause incomplete stress release in the fiber.
Existing UV curing furnaces generally uses an air extraction system to reduce the temperature in the UV curing furnace (and to prolong a life of the UV curing furnace) and to extract volatiles of surface coating material of the optical fiber to improve the processing quality of the optical fiber. Simultaneously, an exhaust system is used to remove harmful gases, so that the extracted volatiles do not pollute the surrounding environment and create hazards to health. A wind speed of the exhaust system should be not too fast or too slow, so that curing of the fiber is not affected. The wind speed of the exhaust system should be kept constant and stable.
The exhaust pipe is prone to blockages after long usages in the production processes, resulting in a decrease in wind speed. Therefore, the exhaust pipe must be manually monitored and adjusted during the shutdown to ensure the wind, speed remains constant and stable. The curing process can be affected by human factors for needing monitoring and adjusting manually. When a problem occurs during the curing or the coating processes of optical fiber production, the production may need to be forcibly terminated so the flow rate can be monitored or adjusted. During normal productions, the actual flow rate of the exhaust cannot be monitored or adjusted.
An optical fiber with low transmission losses and large effective area and a method of manufacturing the optical fiber and a system of manufacturing the optical fiber are disclosed herein.